Synthesis of undoped and Zn doped hausmannite Mn 3O 4 nanorods was achieved through a simple hydrothermal route. Scanning electron microscopic studies showed that due to in situ Zn doping a structural deformation from Mn 3O 4 nanorods to a mixture of Mn 3O 4 nanorods and nanoparticles occurred. The amount of nanoparticles in the mixture increased with the increase of doping percentage. X-ray diffraction studies, transmission electron microscopy and selected area electron diffraction pattern revealed that both the nanorods and the nanoparticles were hausmannite Mn 3O 4. X-ray photoelectron spectroscopic studies confirmed successful zinc doping in Mn 3O 4. Microscopic studies revealed that the average diameters of Mn 3O 4 nanorods and nanoparticles were of 200 nm and 70 nm, respectively. The possible growth mechanism and the reasons behind the formation of nanoparticles along with nanorods are discussed briefly. UV-vis spectroscopic studies showed a continuous increase in the energy bandgap of Mn 3O 4 with the increase in Zn doping percentage. © 2011 Elsevier Ltd. All rights reserved.